High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorption and reaction of CO on the Mo(100)-c(2×2)N surface. CO directly adsorbed on the N atoms from the c(2×2) l...High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorption and reaction of CO on the Mo(100)-c(2×2)N surface. CO directly adsorbed on the N atoms from the c(2×2) layer to form isocyanate (NCO) surface species was found in addition to CO adsorbed on the molybdenum atoms at 120 K. indicating that both Mo and N atoms of the Mo(100)-c(2×2)-N surface are of high reactivities for CO adsorption.展开更多
High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorPtion and decomposition of 15NO on the Mo(100)-c(2×2)14N surface. At 140K, the 15NO molecu1e could adsorb associati...High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorPtion and decomposition of 15NO on the Mo(100)-c(2×2)14N surface. At 140K, the 15NO molecu1e could adsorb associatively on atop sites of the Mo and l4N atoms in the nitride layers. On the other hand, a small amount of dissociatCd 15NO also exists. The dissociation of surface nitric oxides species at elevated temperatures caused the oxidation of the surface Mo.展开更多
低温(110～130K)下,将次表层Fe结构的Pt-Fe模型催化剂(即Pt/Fe/Pt(111)结构)暴露于不同量CO气体,经不同温度退火后,采用高分辨电子能量损失谱(HREELS)研究催化剂表面CO分子的振动谱。结果表明,当CO的暴露量低于0.2 L (Langmuir)时,Pt/Fe...低温(110～130K)下,将次表层Fe结构的Pt-Fe模型催化剂(即Pt/Fe/Pt(111)结构)暴露于不同量CO气体,经不同温度退火后,采用高分辨电子能量损失谱(HREELS)研究催化剂表面CO分子的振动谱。结果表明,当CO的暴露量低于0.2 L (Langmuir)时,Pt/Fe/Pt(111)表面只存在顶位吸附;当暴露量大于0.4L,除了顶位吸附外,桥位吸附开始出现;顶位吸附分子的C-O键振动峰随着暴露量的增加不断向高波数方向偏移。退火温度影响Pt/Fe/Pt(111)表面CO的吸附形式,低于255K时,顶位吸附分子的脱附速率大于桥位吸附分子;高于255 K时,桥位吸附分子的脱附速率较大,并先于顶位吸附的CO从表面完全脱附,其完全脱附温度比Pt(111)表面低50 K。展开更多
The reaction of phenol on metal surface has drawn much attention because of thetechnological importance of phenol in catalysis.Due to the progress of modern surfacescience techniques,it is possible to investigate the ...The reaction of phenol on metal surface has drawn much attention because of thetechnological importance of phenol in catalysis.Due to the progress of modern surfacescience techniques,it is possible to investigate the interaction of complex organic moleculeswith metal surfaces at the microscopic level.However,only very few reports appear in litera-ture on characterization of phenol on Cu(110),and some transition metals,namelyPd(110),Rh(111) and Ni(110).These investigations released the展开更多
The coadsorption of cyclohexanone and oxygen on Pt(111) has been investigated by HREELS and TDS. At 205 K the presence of oxygen induces an "extra" red\|shift of the C--O stretching of coadsorbed cyclohexano...The coadsorption of cyclohexanone and oxygen on Pt(111) has been investigated by HREELS and TDS. At 205 K the presence of oxygen induces an "extra" red\|shift of the C--O stretching of coadsorbed cyclohexanone. Heating this coadsorbed surface from 205 to 250 K leads to further dehydrogenation to form intermediate species and to complete disappearance of the C--O stretching band. Above 300 K, the molecule rings of dehydrogenation species cleave to form hydrocarbon fragments and CO molecules which directly desorb into the vacuum or react with preadsorbed oxygen to produce CO\-2 which leave the surface immediately. TDS results provide further evidence that the preadsorbed oxygen promotes the decomposition of cyclohexanone.展开更多
An investigation has been made on the adsorption and decomposition of formic acid on slightly oxidized Nb(110) surface (0/Nb atom ratio = 0.2) using high resolution electron energy loss spectroscopy (HREELS),and a cor...An investigation has been made on the adsorption and decomposition of formic acid on slightly oxidized Nb(110) surface (0/Nb atom ratio = 0.2) using high resolution electron energy loss spectroscopy (HREELS),and a corresponding surface reaction mode is given.At 140 K,formic acid of low exposure on such an Nb(110) surface decomposed to formate,which bonded on Nb in monodentate configuration,simultaneously some formate decomposed to CO,which adsorbed on the surface.Formic acid multilayers formed when the exposure was high.While the temperature was increased to above 190 K,multilayer formic acid desorbed,and the surface was covered with mon-odentate-bonded formate and CO.In the temperature range of 250-300 K,chemisorbed formate changed from monodentate configuration into bridging configuration and CO molecules disappeared.The decomposition of formate at higher temperatures led to the oxidation of Nb.The formate formed in the high exposure case was so stable that it did not decompose even the temperature展开更多
基金the financial support of this work by the National Natural Science Foundation of China!29873048 ,29873042
文摘High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorption and reaction of CO on the Mo(100)-c(2×2)N surface. CO directly adsorbed on the N atoms from the c(2×2) layer to form isocyanate (NCO) surface species was found in addition to CO adsorbed on the molybdenum atoms at 120 K. indicating that both Mo and N atoms of the Mo(100)-c(2×2)-N surface are of high reactivities for CO adsorption.
文摘High resolution electron energy loss spectroscopy (HREELS) has been used to investigate the adsorPtion and decomposition of 15NO on the Mo(100)-c(2×2)14N surface. At 140K, the 15NO molecu1e could adsorb associatively on atop sites of the Mo and l4N atoms in the nitride layers. On the other hand, a small amount of dissociatCd 15NO also exists. The dissociation of surface nitric oxides species at elevated temperatures caused the oxidation of the surface Mo.
文摘低温(110～130K)下,将次表层Fe结构的Pt-Fe模型催化剂(即Pt/Fe/Pt(111)结构)暴露于不同量CO气体,经不同温度退火后,采用高分辨电子能量损失谱(HREELS)研究催化剂表面CO分子的振动谱。结果表明,当CO的暴露量低于0.2 L (Langmuir)时,Pt/Fe/Pt(111)表面只存在顶位吸附;当暴露量大于0.4L,除了顶位吸附外,桥位吸附开始出现;顶位吸附分子的C-O键振动峰随着暴露量的增加不断向高波数方向偏移。退火温度影响Pt/Fe/Pt(111)表面CO的吸附形式,低于255K时,顶位吸附分子的脱附速率大于桥位吸附分子;高于255 K时,桥位吸附分子的脱附速率较大,并先于顶位吸附的CO从表面完全脱附,其完全脱附温度比Pt(111)表面低50 K。
基金Project supported by the National Natural Science Foundation of China.
文摘The reaction of phenol on metal surface has drawn much attention because of thetechnological importance of phenol in catalysis.Due to the progress of modern surfacescience techniques,it is possible to investigate the interaction of complex organic moleculeswith metal surfaces at the microscopic level.However,only very few reports appear in litera-ture on characterization of phenol on Cu(110),and some transition metals,namelyPd(110),Rh(111) and Ni(110).These investigations released the
文摘The coadsorption of cyclohexanone and oxygen on Pt(111) has been investigated by HREELS and TDS. At 205 K the presence of oxygen induces an "extra" red\|shift of the C--O stretching of coadsorbed cyclohexanone. Heating this coadsorbed surface from 205 to 250 K leads to further dehydrogenation to form intermediate species and to complete disappearance of the C--O stretching band. Above 300 K, the molecule rings of dehydrogenation species cleave to form hydrocarbon fragments and CO molecules which directly desorb into the vacuum or react with preadsorbed oxygen to produce CO\-2 which leave the surface immediately. TDS results provide further evidence that the preadsorbed oxygen promotes the decomposition of cyclohexanone.
基金supported by the National Natural Science Foundation of China
文摘An investigation has been made on the adsorption and decomposition of formic acid on slightly oxidized Nb(110) surface (0/Nb atom ratio = 0.2) using high resolution electron energy loss spectroscopy (HREELS),and a corresponding surface reaction mode is given.At 140 K,formic acid of low exposure on such an Nb(110) surface decomposed to formate,which bonded on Nb in monodentate configuration,simultaneously some formate decomposed to CO,which adsorbed on the surface.Formic acid multilayers formed when the exposure was high.While the temperature was increased to above 190 K,multilayer formic acid desorbed,and the surface was covered with mon-odentate-bonded formate and CO.In the temperature range of 250-300 K,chemisorbed formate changed from monodentate configuration into bridging configuration and CO molecules disappeared.The decomposition of formate at higher temperatures led to the oxidation of Nb.The formate formed in the high exposure case was so stable that it did not decompose even the temperature
